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April Snow and a Temperature Rebound

April 14, 2017

April Snow and a Temperature Rebound:

Thunder and showers later on Sunday gave way to cooler temperatures and snow on Monday across portions of Minnesota. At times Monday night (April 10) into early Tuesday morning, snow showers were heavy for brief periods of time. Total snow accumulation across portions of central and southern Minnesota ranged from 1 to 3 inches in many spots. Observers in North Branch (Chisago County) and New Hope (northern Hennepin County) reported over 5 inches. Following the snow, the coldest temperatures of the month so far were reported, Many northern observers reported morning lows in the teens, while Embarrass and Seagull Lake went down to 12F. However a quick warm-up followed and the heavy, wet snow melted rapidly with temperatures climbing into the 50s and 60s F.

Over the first 9 days of April, the temperature pattern was consistently warmer than normal, with reports of four new record maximum temperatures set, including 81 degrees at Marshall on the 9th, and reports of 16 new daily record warm minimum temperature records. With the generally warmer than normal weather this month, soil temperatures have climbed into the upper 40s F and low 50s F around much of the state. This has motivated farmers to think about planting, and some spotty field activity was observed around the state this week. I suspect next week will bring a significant amount of corn planting.

An Apology for Comments on Temperature Trends:

Last week I made a gross error in judgement in describing the change in monthly values of temperature using percentages. This was stupid! There are at least three scales used for measuring temperature (Celsius, Fahrenheit, and Kelvin) all giving drastically different answers in terms of percentage changes which don't really make any sense. My point in writing about temperature change was simply to illustrate that the changes in value have been larger in the months of December, January, February, and March (3°F to 6°F) than they have in other months. And further that the change in July has been relatively minor (1F). It is important to understand that the measured climate changes in our states are not equal in all months. I am sorry for creating confusion by referencing percentages.

Weekly Weather Potpourri:

Tropical Cyclone Cook struck New Zealand this week with very heavy rains and strong winds. This large storm cut a wide swath of damages due to flooding and wind. Some areas reported wind speeds up to 100 mph and gusts to 125 mph causing broken trees and down power lines. Several inches of rain fell in widespread areas, and flooded roads and highways were closed. Initial assessment was that Cook is the strongest cyclone to hit New Zealand in decades.

NOAA scientists described a new satellite based tool for assessing the onset of drought across the American landscape. It is called the Evaporative Stress Index (ESI) and is derived from GOES satellite measurements. With this imagery areas where drought may be developing can be assessed and compared to the weekly Drought Monitor maps.

The Climate Explorer, a NOAA web-based tool for examining climate maps, graphs, and data tables at the county level has been nominated for the annual Webby Awards in the Best Visual Design Category. It is interesting to compare the climates of different regions with each state.

A new international research study finds that climate change will thaw about 20 percent more permafrost landscape than previously thought. Scientists from the United Kingdom Meteorological Office discussed these findings earlier this week. When permafrost thaws greenhouse gases are released into the atmosphere, and in addition the soil becomes less stable and there is often damage to structures built on it. Approximately 35 million people live on permafrost landscapes.

MPR listener question:

It was difficult driving in the snow storm Monday night this week, very heavy at times. What is the largest amount of snow we have received in the state during the month of April?

Answer:

Well, I will answer that in two different time frames. On a daily basis, the largest amount ever was 28 inches at Pigeon River (Cook County) back on April 5, 1933. For a monthly total snowfall, several climate stations have reported over 40 inches in April, with Duluth and Two Harbors getting over 50 inches of snow during April of 2013. So a few inches in April is "nuisance snow."

Twin Cities Almanac for April 14th:

The average MSP high temperature for this date is 57 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 37 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for April 14th:

MSP records for this date include: highest daily maximum temperature of 89 degrees F in 2003; lowest daily maximum temperature of 32 degrees F in 1928; lowest daily minimum temperature of 18 degrees F in 1926 and 1928; highest daily minimum temperature of 64 F in 2003; record precipitation of 1.56 inches in 1983. Record snowfall on this date is 13.6 inches from the same storm in 1983.
Average dew point for April 14th is 31F; the maximum dew point on this date is 61F in 1976; and the minimum dew point on this date is 7F in 1928.

All-time state records for April 14th:

The all-time state high temperature for today's date is 94 degrees F at Benson (Swift County) and Milan (Chippewa County) in 2003; the all-time state low for today's date is -5 degrees F at Roseau in 1950. The all-time state record precipitation for this date is 2.95 inches at Northfield (Rice County) in 1886. The all-time state record snowfall for this date is 16.0 inches at Farmington (Dakota County) in 1983 and at Mankato (Blue Earth County) in 1928.

Past Weather Features:

By far the most significant historical weather event on April 14th in Minnesota history was the devastating EF-4 tornado that destroyed Sauk Rapids on the afternoon of April 14, 1886. This tornado, at times 800 yards wide passed over the Mississippi River and sucked it dry for a few minutes. It destroyed a school, a post office, two churches, and a bridge in Sauk Rapids injuring over 200 people and killing 72 others, including several members of an outdoor wedding party.

The coldest April 14 occurred in 1950 when morning lows ranged from single digits to the teens across most of the state. Places in the north like Roseau and Warroad saw subzero temperatures and daytime highs did not reach the freezing mark.

A spring snow storm brought heavy snow to many parts of the state over April 14, 1983. Heavy, wet snow covered portions of southern and central Minnesota, bringing down large tree limbs, as well as power lines. In St Cloud a 90 foot tall tower was toppled by over 50 mph winds. Some roads were closed due to blizzard conditions as some climate stations in southern and central Minnesota reported 12 to 19 inches of snow.

The warmest April 14th was in 2003, when 25 Minnesota communities saw the mercury climb to 90°F or greater. Even Warroad up by Lake of the Woods reached an afternoon high of 80 degrees F.

Outlook:

Warm and wet on Saturday with widespread showers and a chance for thunderstorms. Cooler and breezy for Easter Sunday, with highs in the 50s F, somewhat near normal. Chance of showers again by Tuesday, with temperatures averaging a few degrees F warmer than normal most of next week.